The present invention generally relates to variable transmission windows. More specifically, the present invention relates to control systems for controlling the transmission of variable transmission windows and to various constructions of variable transmission windows and methods for making variable transmission windows.
Variable transmittance light filters, such as electrochromic light filters, have been proposed for use in architectural windows, skylights, and in windows, sunroofs, and rearview mirrors for automobiles. Such variable transmittance light filters reduce the transmittance of direct or reflected sunlight during daytime through the window, while not reducing such transmittance during nighttime. Not only do such light filters reduce bothersome glare and ambient brightness, but they also reduce fading and generated heat caused by the transmission of sunlight through the window.
Variable transmission windows have not been widely accepted commercially for several reasons. First, they tend to be very expensive due to the cost of materials required for their construction, and their complex construction can make mass-production difficult. Additionally, electrochromic windows tend to have a lower life expectancy than conventional windows due to degradation of the electrochromic materials used in the windows. The combination of added cost and lower life expectancy has deterred many architects, designers, and builders from using electrochromic windows.
Variable transmission windows have also not been widely accepted commercially in vehicles designed for the transportation of passengers, such as, for example, busses, airplanes, trains, ships, and automobiles. The inventors have recognized that providing for the use of variable transmission windows in these types of vehicles provides challenges in addition to those already noted above. These challenges can include, but are not limited to, providing effective, coordinated, individual and central control of multiple variable transmission windows, providing multiple modes of operation responsive to individual or collective passenger needs, providing the ability to quickly change window transmittance states, minimizing system power consumption, protecting against environmental factors such as moisture and power surges, protecting windows from excessive heat and physical external loads, and providing user interfaces allowing relatively unsophisticated users to understand and control the windows. The inventors have also recognized that manufacturing challenges can prove a barrier to providing system features needed to address the above-identified needs.